Audio Trimmer Skill | Agent Skills

Audio Trimmer

Edit audio files with precise cutting, trimming, and effects. Extract segments, add fades, adjust speed, concatenate clips, and apply basic audio manipulations.

Quick Start

from scripts.audio_trimmer import AudioTrimmer

# Trim to segment
trimmer = AudioTrimmer("podcast.mp3")
trimmer.trim(start="00:05:30", end="00:10:00")
trimmer.save("segment.mp3")

# Add fades and save
trimmer = AudioTrimmer("song.mp3")
trimmer.fade_in(3000).fade_out(5000).save("song_faded.mp3")

# Concatenate multiple files
AudioTrimmer.concatenate(["intro.mp3", "main.mp3", "outro.mp3"], "full_episode.mp3")

Features

Precise Trimming: Cut segments by timestamp or milliseconds
Fade Effects: Fade in/out with customizable duration
Speed Control: Speed up or slow down audio
Concatenation: Join multiple audio files
Basic Effects: Reverse, loop, overlay
Silence Operations: Add silence, remove silence
Volume Adjustment: Gain control, normalization

API Reference

Initialization

trimmer = AudioTrimmer("audio.mp3")

Trimming

# By timestamp (HH:MM:SS or MM:SS)
trimmer.trim(start="01:30", end="05:00")

# By milliseconds
trimmer.trim(start_ms=90000, end_ms=300000)

# From start to timestamp
trimmer.trim(end="02:00")

# From timestamp to end
trimmer.trim(start="10:00")

Fade Effects

# Fade in at start (milliseconds)
trimmer.fade_in(3000)  # 3 second fade in

# Fade out at end
trimmer.fade_out(5000)  # 5 second fade out

# Crossfade (for concatenation)
AudioTrimmer.concatenate_with_crossfade(files, output, crossfade_ms=2000)

Speed Control

# Speed up (1.5x)
trimmer.speed(1.5)

# Slow down (0.75x)
trimmer.speed(0.75)

Effects

# Reverse audio
trimmer.reverse()

# Loop audio N times
trimmer.loop(3)

# Overlay another audio
trimmer.overlay("background.mp3", position_ms=0, volume=-6)

Volume

# Adjust volume (dB)
trimmer.gain(6)   # Increase by 6 dB
trimmer.gain(-3)  # Decrease by 3 dB

# Normalize to target level
trimmer.normalize(-3)  # Normalize to -3 dBFS

Silence Operations

# Add silence at start
trimmer.add_silence_start(2000)  # 2 seconds

# Add silence at end
trimmer.add_silence_end(1000)

# Strip leading/trailing silence
trimmer.strip_silence(threshold=-50)  # dBFS threshold

Concatenation

# Simple concatenation
AudioTrimmer.concatenate(
    ["file1.mp3", "file2.mp3", "file3.mp3"],
    "output.mp3"
)

# With crossfade
AudioTrimmer.concatenate_with_crossfade(
    ["intro.mp3", "main.mp3", "outro.mp3"],
    "output.mp3",
    crossfade_ms=2000
)

Save

# Save to file (format from extension)
trimmer.save("output.mp3")

# Explicit format and quality
trimmer.save("output.mp3", format="mp3", bitrate=320)

CLI Usage

# Trim segment
python audio_trimmer.py --input podcast.mp3 --output segment.mp3 --start 05:30 --end 10:00

# Add fades
python audio_trimmer.py --input song.mp3 --output faded.mp3 --fade-in 3000 --fade-out 5000

# Speed up
python audio_trimmer.py --input lecture.mp3 --output fast.mp3 --speed 1.5

# Concatenate files
python audio_trimmer.py --concat file1.mp3 file2.mp3 file3.mp3 --output merged.mp3

# Extract multiple segments
python audio_trimmer.py --input podcast.mp3 --segments "00:00-05:00,10:00-15:00,20:00-25:00" --output-dir ./clips/

CLI Arguments

| Argument | Description | Default | |----------|-------------|---------| | --input | Input audio file | Required | | --output | Output file path | Required | | --start | Start timestamp (HH:MM:SS or MM:SS) | - | | --end | End timestamp | - | | --fade-in | Fade in duration (ms) | - | | --fade-out | Fade out duration (ms) | - | | --speed | Speed multiplier | 1.0 | | --gain | Volume adjustment (dB) | 0 | | --reverse | Reverse audio | False | | --normalize | Normalize to dBFS level | - | | --concat | Files to concatenate | - | | --crossfade | Crossfade duration for concat (ms) | 0 | | --segments | Multiple segments to extract | - |

Examples

Extract Podcast Segment

trimmer = AudioTrimmer("episode_42.mp3")
trimmer.trim(start="15:30", end="22:45")
trimmer.fade_in(1000)
trimmer.fade_out(2000)
trimmer.save("highlight_clip.mp3")

Create Ringtone

trimmer = AudioTrimmer("song.mp3")
trimmer.trim(start="01:15", end="01:45")  # 30-second segment
trimmer.fade_in(500)
trimmer.fade_out(1000)
trimmer.normalize(-3)
trimmer.save("ringtone.mp3", bitrate=192)

Speed Up Lecture

trimmer = AudioTrimmer("lecture.mp3")
trimmer.speed(1.25)  # 25% faster
trimmer.normalize(-16)  # Podcast-friendly level
trimmer.save("lecture_fast.mp3")

Build Episode from Segments

# With crossfades between segments
AudioTrimmer.concatenate_with_crossfade(
    files=[
        "intro_music.mp3",
        "sponsor_read.mp3",
        "main_content.mp3",
        "outro_music.mp3"
    ],
    output="full_episode.mp3",
    crossfade_ms=1500
)

Extract Multiple Highlights

# Extract several segments from a long recording
trimmer = AudioTrimmer("meeting_recording.mp3")

segments = [
    ("00:05:00", "00:08:30", "intro"),
    ("00:25:00", "00:32:00", "discussion"),
    ("01:15:00", "01:20:00", "conclusion")
]

for start, end, name in segments:
    t = AudioTrimmer("meeting_recording.mp3")
    t.trim(start=start, end=end)
    t.fade_in(500)
    t.fade_out(500)
    t.save(f"{name}.mp3")

Add Background Music

# Overlay quiet background music
trimmer = AudioTrimmer("podcast.mp3")
trimmer.overlay(
    "ambient_music.mp3",
    position_ms=0,
    volume=-15,  # 15 dB quieter
    loop=True    # Loop to fill duration
)
trimmer.save("podcast_with_music.mp3")

Time Format Reference

The trimmer accepts these timestamp formats:

| Format | Example | Meaning | |--------|---------|---------| | MM:SS | 05:30 | 5 minutes 30 seconds | | HH:MM:SS | 01:30:00 | 1 hour 30 minutes | | SS | 90 | 90 seconds | | SS.ms | 90.500 | 90.5 seconds |

Dependencies

pydub>=0.25.0

Note: Requires FFmpeg installed on system.

Limitations

Speed adjustment may affect pitch (no pitch preservation)
Very large files may consume significant memory
Crossfade works best with similar audio levels

Agent Skills: Audio Trimmer

Skill Files